This is a competing renewal of our program on the role of micronutrients among HIV-infected individuals. In the past cycle we have determined that multivitamins supplementation slows disease progression in pre-antiretroviral therapy stages of disease. Access to ART in developing countries is limited but is gradually becoming standard of care. The safety and efficacy of micronutrient supplements in the context of ART have not been established. We propose to examine the relationships between supplementation with multivitamins (including B-complex, C and E) and disease progression and immune reconstitution among Tanzanian women and men who are on ART. We will enroll 3000 HIV positive adult women and men who are on ART or who are on and will initiate ART at the time of enrollment. Patients will be randomized using a to: (a) multivitamins including multiples of the RDA as previously used; (b) low dose multivitamin supplements at 1 RDA level. Research physicians and nurses at a study clinic will see study participants on monthly basis to assess clinical status and undertake study procedures. Each individual will be followed up for a minimum of 24 months, or to a common closing date at the end of the study (a maximum of 48 mo), or his/her death or loss to follow-up. Home visits will be done as appropriate to follow up on individuals who have not come for their scheduled visits. Nutritional assessment will be done using anthropometric, biochemical and dietary methods. All patients will be provided with standard of care as per national guidelines. CD4 cell counts and complete blood counts are routinely done for all patients on ART. Lymphocyte proliferation and Th-1 cytokines will be measured in a sub sample of 800 patients. Plasma viral load will be measured at four time points during the study. Micronutrient supplements may be a low cost intervention that preserves limited drug combinations in the therapy arsenal to later in the disease and enhance the quality of life of patients. The study is a collaborative effort between Harvard School of Public Health and Muhimbili University College of Health Sciences, Dar-es-Salaam, Tanzania.